Question

What does { } mean? http://prntscr.com/4og3wo

Answer 1

curly braces { } are used to denote sets

sets are collections of things (in math, usually it's numbers)

Answer 2

set D is the set of numbers divisible by 3 from 1 to 15, so D is

D = {3, 6, 9, 12, 15}

Answer 3

Yes but the blank one... What does that one mean?

Answer 4

oh that means the empty set. There are no elements in the set

Answer 5

Oh ok Thank You! c:

Answer 6

you can also write that as \(\Large \emptyset\)

Answer 7

you're welcome